From d02b74a5dcfed4bfc8f2f8e545bca4d2afabb296 Mon Sep 17 00:00:00 2001
From: Googler <noreply@google.com>
Date: Fri, 27 Apr 2018 10:37:02 -0700
Subject: Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463
---
 pkg/sentry/hostcpu/getcpu_amd64.s | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 pkg/sentry/hostcpu/getcpu_amd64.s

(limited to 'pkg/sentry/hostcpu/getcpu_amd64.s')

diff --git a/pkg/sentry/hostcpu/getcpu_amd64.s b/pkg/sentry/hostcpu/getcpu_amd64.s
new file mode 100644
index 000000000..7f6247d81
--- /dev/null
+++ b/pkg/sentry/hostcpu/getcpu_amd64.s
@@ -0,0 +1,24 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "textflag.h"
+
+// func GetCPU() (cpu uint32)
+TEXT ·GetCPU(SB), NOSPLIT, $0-4
+	BYTE $0x0f; BYTE $0x01; BYTE $0xf9; // RDTSCP
+	// On Linux, the bottom 12 bits of IA32_TSC_AUX are CPU and the upper 20
+	// are node. See arch/x86/entry/vdso/vma.c:vgetcpu_cpu_init().
+	ANDL	$0xfff, CX
+	MOVL	CX, cpu+0(FP)
+	RET
-- 
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